Injury-triggered renarrowing (restenosis) of arteries treated with angioplasty to relieve atherosclerotic obstruction remains a challenge due to a lack of therapies combining adequate efficacy and safety. Strategies aimed at accelerated vascular healing and endothelium regeneration have potential to prevent restenosis while avoiding the side effects of the currently used therapies. However, in order to realize this potential a significant improvement in their efficiency is required. This proposal is concerned with an integrated drug-in-cell antirestenotic strategy based on dual functionalization of endothelial cell with drug-loaded magnetic nanocarriers to provide them with capacity for stent-targeted delivery and enhanced antirestenotic effectiveness. The latter is achieved by inducing and activating endothelial nitric oxide synthase with estradiol formulated in magnetic nanoparticles (MNP) in the form of its precursor, estradiol benzoate (E2Bz). The present studies will establish feasibilit of using this approach for preventing in-stent restenosis and achieving facilitated reendothelialization in a validated rat model of atherosclerosis reproducing key features of human disease .The following specific aims will be addressed: AIM 1: Drug-in-cell approach evaluation and optimization in culture and co-culture studies. E2Bz-loaded biodegradable MNP will be formulated, and their size, composition, magnetic properties and drug release profile will be characterized. Cell compatibility, internalization and degradation kinetics of MNP, as well as E2Bz-induced nitric oxide synthesis by MNP-functionalized endothelial cells and its growth inhibitory effect on co-cultured smooth muscle cells will be the main endpoints of the Aim 1 experiments. AIM 2: Targeting, reendothelialization and efficacy studies. Arterial localization, tissue distribution and endothelium recovery after magnetically targeted delivery of functionalized cells will be studied in the rat atherosclerosis/ carotid stenting model. The extent of restenosis will be determined two weeks post-delivery by computerized morphometry, and the pharmacological effect of cell functionalization will be delineated using animals treated with cells loaded with blank MNP as controls.